1. Field of Invention                The invention relates to a printing plate cylinder that includes a cylinder mandrel and a sleeve, and a male register element and a female register element that facilitate the alignment of the mandrel and the sleeve.        
2. Description of the Prior Art
In this print from printing plate cylinder those types of print cylinders are understood which carry a print impression. Printing plate cylinders are often made from different cylindrical shaped elements. As a rule a rotary base mandrel fixed at a machine frame forms the core of such a printing plate cylinder. It is clear that for changing tasks this mandrel is acted on by different print sleeves which carry different print impressions. For this purpose the printing sleeve is pulled over the base mandrel.
Besides these printing sleeves there are also known adapter sleeves which are also pulled over the base mandrel and fit the circumference of the thus formed cylinder core to the individually required print length. Often over this adapter sleeve either a further adapter cylinder or a print sleeve is slid anew. Such methods are for example known from Flexo Printing. In particular in Flexo Package Printing one has to do with a number of different print lengths which require many different adapters. The corresponding printing requirements are often satisfied with central cylinder flexo print machines. There are many adapter machines under these machines. The printing cases of these machines often carry a print-sleeve or a print-plate made from one of flexible material characteristic of flexo-print.
For all multi-color print processes the necessity to perform a register control or regulation is known to arise. It needs to begin with a basic determination of the position of different parts of the printing plate cylinder (such as printing mandrel and printing sleeve) to each other.
Thus EP 782 919 A1 suggests for setting up of side registers, to pull a printing sleeve axially over a print mandrel till the front end of this sleeve arrives at a pin on the mandrel acting as a block. The axial position of the sleeve on the mandrel is determined because a further moving pin on the circumferential surface of the mandrel is backed out in radial direction and works against the back end of the sleeve.
For this purpose the position of the print impression in the different color works relative to each other has to be determined. Therefore the position of the print impression relative to the base mandrel of the machine control or the machine operator must be known. For this the base mandrels of the print cylinder normally have register pins which protrude from the circumferential surface of the mandrel. The sleeves which cover the base mandrel have slots in which the pins either grip or snap if the sleeve reaches its set position relative to the mandrel. In this way the angular position of the sleeve to the mandrel is aligned and determined. If the sleeve is an adapter sleeve then at least a further sleeve—namely the print sleeve at least—must be brought to a fixed angular position on this sleeve and thus on the base mandrel. For this purpose the adapter sleeve has a register pin again which protrudes from its outer surface and grips a slot of the further sleeve for this purpose when it reaches its set position. This form of pre-registering had been known for a long time and is well implemented even in the so called directly driven print machines in which each print plate cylinder has its own drive as well as in machines in which operational connections exist between different cylinders. Printing plate cylinders which are made from such base mandrels and sleeves and are aligned or registered in this way can be described in the following way:
Printing plate cylinder which at set up of the printing machine is made from at least following cylindrical shaped elements:                A cylinder core which is placed in the print machine as rotary and        a sleeve which can be pulled over the cylinder core at least partly        whereby the angular position of both these elements to each other is settable as adjustable through following means:        A male register element which is fixed on one of the two elements to be aligned,        a female register element which is part of the corresponding other element to be aligned,        whereby both the register elements previously mentioned stand in working connection with each other if the elements to be aligned are in the set position relative to each other.        
The print sleeve of one such printing plate cylinder is described in DE 41 40 768 A1.                Here it is to be observed that a cylinder core in above sense is often understood to be the base mandrel. However in the sense of this print the concept cylinder core also includes a base mandrel which is acted upon with one or several sleeves. A male register element is often available as a pin or some other protrusion which protrudes from the outer circumferential surface of the cylinder core or the inner circumferential surface of a further sleeve. A female register element is in the position to make a working connection—in first line a form of binding—with the male register element.        
At set up or putting together of this printing plate cylinder according to current technology however there appear damages on register elements as well as on the sleeves. This can be attributed to the fact that the sleeves are not slid correct to the angle on the cylinder core so that the female register elements—in first line as slots—miss the register pins whereby at the end of the sliding movement it comes to collisions between the edges of the sleeves and the male register elements—up to now pins as a rule. Damages on the register elements as well as the edges of the wrapped sleeves are the result.